Oral Delivery of SARS-CoV-2 DNA Vaccines Using Attenuated Salmonella typhimurium as a Carrier in Rat.

The 2019 novel coronavirus disease (COVID-19) is the disease that has been identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the prophylactic treatment of SARS-CoV-2 is still under investigation. The effective delivery of eukaryotic expression plasmids to the immune system's inductive cells constitutes an essential requirement for generating effective DNA vaccines. Here, we have explored the use of Salmonella typhimurium as vehicles to deliver expression plasmids orally. The attenuated Salmonella phoP was constructed by the one-step gene inactivation method, and plasmid-encoded the spike protein of SARS-CoV-2 was transform into the Salmonella phoP by electroporation. Western blot experiment was used for the detection of SARS-CoV-2 expression on 293T cells. Wistar rats were immunized orally with Salmonella that carried a eukaryotic expression plasmid once a week for three consecutive weeks. The ELISA was performed to measure the SARS-CoV-2 specific IgG at rat's serum samples. pSARS-CoV-2 can be successfully expression on 293T cells, and all immunized animals generated immunity against the SARS-CoV-2 spike protein, indicating that a Salmonella-based vaccine carrying the Spike gene can elicit SARS-CoV-2-specific secondary immune responses in rats. Oral delivery of SARS-CoV-2 DNA vaccines using attenuated Salmonella typhimurium may help develop a protective vaccine against SARS-CoV-2 infection.

Biological activities of Egyptian grape and mulberry by-products and their potential use as natural sources of food additives and nutraceuticals foods

Interest in the biological role of bioactive compounds present in plant by-products has increased over the last few years. This study aimed to investigate the nutritive value and biological activities of Egyptian Grape leaves (GL), Grape seeds (GS) and Mulberry leaves (ML), as well as investigate the impact of P-irradiation for improving the utilization of these plant by-products. The dose level 5.0 kGy showed highest the content of crude protein (24.42, 19.41 and 13.50 mg/100 g), as well as crude fiber (34.26 and 21.18 mg/100 g) for ML, GL and GS, respectively. Mulberry leaves has a highest content of protein and fiber at dose 5.0 kGy compared with GL and GS. The highest total phenolic content was found in GS (9.75 mg/g DW), followed by GL (7.32 mg/g DW) and the lowest in ML (5.97 mg/g DW). While ML had a higher total flavonoids content (5.61 mg/g DW) than GS (4.88 mg/g DW) and GL (2.86 mg/g DW). Total phenolic and flavonoid contents were significantly increased at 5.0 kGy. The highest level (83.25% and 80.24%) of scavenging activity (DPPH %) and inhibition activity of HCT 116 cells was recorded at 5.0 kGy by GS. All extracts irradiated at 5.0 kGy exhibited varying degrees of antibacterial activity against (Gram+ve and Gram-ve), the GS followed by GL then ML showed strong antibacterial activity with a diameter of inhibition zone of 26.2, 24.5 and 19.7 mm, against L. monocytoganes, respectively and 24.4, 21.4 and 17.2 against S. typhimurium, respectively. This study suggests that P-irradiation is an effective technique to enhance the recovery of phenolics and flavonoids from GL, GS and ML. Also in current study, antioxidant, antibacterial and anticancer activity has been suggested to appear a clear positive relationship with the total phenolic material. This study has proved that the Egyptian GL, GS and ML are rich sources of valuable phytochemicals and nutrients that can serve as a potential source of nutraceuticals and multifunctional food additives (antimicrobial, antioxidant, and anticancer). Phenolic compounds recovered from GL, GS and ML may have a potential role in fighting the COVID-19.

A Study on the Effect of Integrated Ozone and UVC-LED Approaches on the Reduction of Salmonella typhimurium Bacteria in Droplets

In the wake of the SARS-CoV-2 pandemic, inactivating bioaerosols became a pivotal issue which helps to prevent the transmittance of SARS-CoV-2. Thus, the current study was conducted to investigate a potential inactivating method using both ozone (O-3) and ultraviolet C (UVC). Individual and integrated effects of O-3 and UVC were compared. A solution containing approximately 4 similar to 7.3 x 10(6) CFU/mL of Salmonella typhimurium bacteria was used to produce bacteria droplets. These droplets were exposed to O-3 and UVC to determine the reduction rate of bacteria. The exposure times were set as 1 and 30 minutes. Ozone concentrations were 100 and 200 ppmv. UVC-LEDs were used as a UVC source. Peak wavelength of the UVC-LED was 275 nm and the irradiation dose was 0.77 mW/cm(2). In terms of O-3 and UVC-LED interaction, 194 ppmv styrene was used as a target compound to be removed. Considering the O-3 and UVC-LED interaction, the presence of O-3 could reduce the performance of the UVC-LED, and UVC-LED could also reduce significant amount of O-3. The sequence of O-3 and UVC-LED treatment was as follows: O-3 was exposed at first, then UVC-LED, and this order showed the best reduction ratio ( > 99.9%). Therefore, if O-3 and UVC-LED is used to disinfect Salmonella typhimurium bacteria contained in droplets, bacteria should be separately exposed to O-3 and UVC-LED in order to improve the inactivation efficiency.

Carrying out pseudo dual nucleic acid detection from sample to visual result in a polypropylene bag with CRISPR/Cas12a.

Amplification-based nucleic acid detection is widely employed in food safety, medical diagnosis and environment monitoring. However, conventional nucleic acid analysis has to be carried out in laboratories because of requiring expensive instruments and trained personnel. If people could do nucleic acid detection at home by themselves, the application of nucleic acid detection would be greatly accelerated. We herein reported a polypropylene (PP) bag-based method for convenient detection of nucleic acids in the oil-sealed space. The PP bag has three chambers which are responsible for lysis, washing and amplification/detection, respectively. After adding sample, nucleic acids are adsorbed on magnetic particles (MPs) and moved into these three chambers successively through immiscible oil channel by an external magnet. Combined with isothermal amplification, the PP bag can be incubated in a water bath or milk warmer and acted as a reaction tube. With highly specific CRISPR technology, Salmonella typhimurium (St) and SARS-CoV-2 can be visually detected in these PP bags within 1 h, indicating its potential household application. To further improve the reliability of nucleic acid testing at home, a logic decision method is introduced by detecting both target and endogenous reference gene. Positive/negative/invalid detection result can be obtained by chronologically adding the CRISPR reagents of target and endogenous reference gene. We anticipate that this PP bag can provide a novel toolkit for nucleic acid detection in people's daily life.